This application claims the priority of German Patent Application No. 197 34 145.4, filed Aug. 7, 1997, the disclosure of which is expressly incorporated by reference herein.
The invention relates to an air conditioner for vehicles having a housing, an evaporator and a heat exchanger which, viewed in the air flow direction, are successively arranged at a distance from one another in the housing and are aligned such that the air passage surfaces of the evaporator and the heat exchanger are situated approximately at a right angle with respect to one another. A housing section, which exists between the evaporator and the heat exchanger and whose bottom is constructed to be descending approximately in a V-shape from the lower edge of the evaporator and ascending to the rear edge of the heat exchanger, has a warm air flap which is arranged in the housing section to be swivellable about a swivel axis between two swivelling end positions and completely blocks the air flow to the heat exchanger in one swivelling end position and opens it up maximally in the other swivelling end position.
In the case of a known air conditioner of the above-mentioned type, such as in European Patent Document EP 0 419 707 B1, the warm air flap is fixed with its swivel axis on the V-shaped bottom of the housing section, specifically in its ascending area. In its blocking position, with its flap edge aligned in parallel to the swivel axis, the warm air flap rests against the edge of the heat exchanger which is in the front viewed in the air flow direction, such that the air passage surface of the heat exchanger is completely shut off. In its release position, the warm air flap rests against the bottom of the housing section. The warm air flap is restrictedly coupled with a cold air flap which is arranged in a bypass, which bypasses the heat exchanger, from the evaporator to a mixing space situated behind the heat exchanger. The warm air flap can take up any intermediate position between its two swivelling end positions. When the warm air flap is fully opened, an air guiding duct is formed between the heat exchanger and the ascending area of the bottom of the housing section, in which air guiding duct the air flow leaving the evaporator is guided to the heat exchanger.
It is an object of the invention to improve an air conditioner of the above-mentioned type such that, on the one hand, a very good air approach flow to the heat exchanger is ensured in all swivel positions of the warm air flap and, on the other hand, a sufficiently good water precipitation is achieved from the air flow which is moisture-laden after flowing through the evaporator.
This and other objects are achieved according to the present invention by an air conditioner for vehicles having a housing, an evaporator and a heat exchanger which, viewed in the air flow direction, are successively arranged at a distance from one another in the housing and are aligned such that the air passage surfaces of the evaporator and the heat exchanger are situated approximately at a right angle with respect to one another. A housing section, which exists between the evaporator and the heat exchanger and whose bottom is constructed to be descending approximately in a V-shape from the lower edge of the evaporator and ascending to the rear edge of the heat exchanger, has a warm air flap which is arranged in the housing section to be swivellable about a swivel axis between two swivelling end positions and completely blocks the air flow to the heat exchanger in one swivelling end position and opens it up maximally in the other swivelling end position. The swivel axis extends at a parallel distance from the flap edge which, viewed in the air flow direction, is in the front and in the rear, and its arrangement in the housing section is such that, in the blocking position of the warm air flap, the rearward flap edge rests against the bottom of the housing section in its ascending area, and the forward flap edge rests against the front edge of the heat exchanger. In the release position of the warm air flap, the rearward flap edge is swivelled in front of the air passage opening of the heat exchanger and the forward flap edge is situated in or close to a horizontal plane extending through the swivel axis.
The air conditioner according to the invention has the advantage that, as a result of the construction and the arrangement of the warm air flap according to the invention, the air, which, when the warm air flap is swivelled out of its blocking position, flows from the evaporator to the heat exchanger, is divided in each swivelling position of the warm air flap into two partial air flows, of which one flows along on the top side of the heat exchanger, and the other is guided in a flow duct formed between the warm air flap and the bottom of the housing section and leads to the heat exchanger. As a result, the warm air flap achieves an air guiding function which improves the approach flow to the heat exchanger. In addition, from the air flows which are restrictedly guided along the warm air flap and the bottom of the housing section, significantly more moisture and water droplets are precipitated in the boundary layer area along the warm air flap and the bottom than from an air flow flowing freely to the heat exchanger. The water droplets which in this case precipitate on the warm air flap and on the bottom are directed to the lowest point of the V-shaped bottom. As a result, the warm air flap also achieves a water separating function such that only already largely dehumidified air flows through the heat exchanger.
Expedient embodiments of the air conditioner according to the invention with advantageous further developments and improvements of the invention are described herein.
According to a preferred embodiment of the invention, a water drainage groove is constructed on the surface of the warm air flap facing the evaporator. The water drainage groove extends in parallel to the swivel axis and, viewed in the air flow direction, in front of the swivel axis and leads out freely at the two longitudinal lateral edges of the warm air flap. In this case, the groove bottom of the water drainage groove is constructed to be descending toward both longitudinal lateral edges of the warm air flap, which can be achieved by a slightly convex curvature of the warm air flap in the direction of its swivel axis symmetrically to the center line. By means of this water drainage groove, the water film forming on the top side of the warm air flap by the water droplets precipitating there is discharged very rapidly and removed from the air flow so that there is no danger that the precipitating water droplets are, in turn, entrained by the air flow.
This effect will still be improved if, according to an advantageous embodiment of the invention, longitudinal grooves, which extend transversely to the water drainage groove, are constructed on the surface of the flap part of the warm air flap situated in front of the swivel axis in the air flow direction, which longitudinal grooves lead out into the water drainage groove. In addition, these longitudinal grooves may lead out freely at the forward flap edge.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.